20421005 has 8 divisors (see below), whose sum is σ = 26733024. Its totient is φ = 14851600.

The previous prime is 20420999. The next prime is 20421013. The reversal of 20421005 is 50012402.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20421005 - 2⁴ = 20420989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 185591 + ... + 185700.

It is an arithmetic number, because the mean of its divisors is an integer number (3341628).

Almost surely, 2^20421005 is an apocalyptic number.

It is an amenable number.

20421005 is a deficient number, since it is larger than the sum of its proper divisors (6312019).

20421005 is a wasteful number, since it uses less digits than its factorization.

20421005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371307.

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 20421005 is about 4518.9606105829. The cubic root of 20421005 is about 273.3331903959. Note that the first 3 decimals are identical.

Adding to 20421005 its reverse (50012402), we get a palindrome (70433407).

The spelling of 20421005 in words is "twenty million, four hundred twenty-one thousand, five".